| With the rapid development of the automobile industry in China,the competitiveness of the industry is becoming more and more intense,and the requirements for the safety performance of the automobile are increasing.It is the goal of the host factory to design a high performance body structure and reduce the quality of the body as far as possible.A new method of ring structure optimization is proposed in this paper.The concept model of a new vehicle is established by using the reverse development design technology of the body.In the conceptual design stage and the detailed finite element design stage,the static stiffness and mode are taken as the measurement standards,and the ring structure is optimized,and a reasonable body structure is designed.The main research work of this paper is as follows?1.Based on the detailed finite element model of the body of the platform vehicle,a conceptual model was built.The accuracy of the model was verified by the bending rigidity and displacement distribution cloud diagrams of the vehicle body.The reliability and accuracy of the conceptual model were illustrated,using the beam element.According to the inverse modelling method of the conceptual model,HyperMesh software was used to establish a conceptual model based on the exterior face of the new model and the overall layout dimensions.NASTRAN software was used to analyze the bending stiffness and modality of the initial model,and the initial model was obtained.The bending stiffness is 7117N·mm-1,the torsional stiffness is 519089 N·m·rad-1,the first-order bending mode is 29.6Hz,and the first-order torsional mode is 26.9Hz.The target values for bending and torsion stiffness of the new model are 8000 N·mm-1 and 650,000 N·m·rad-1,respectively.The first-order bending and torsion stiffness modes are 35 Hz and 30 Hz,respectively.Since these performance can not reach the target of new model,optimization design should be carried out.2.According to the relevant standard,ring structure of newly built white-body concept model is analyzed,and the difference between the ring structure of the body and the 16 ring structures of the conventional body is compared and analyzed from three aspects of the body cross section ring,the longitudinal section ring and the horizontal surface ring.It is found that there are many unreasonable places in the cross section ring structure of the white body,and the loop structure optimization is carried out on this basis,and the optimal body structure of the concept design stage is finally obtained.In the conceptual optimization stage,the bending stiffness is increased by 6.1%,the torsional stiffness is increased by 4%,the first order bending mode is increased by 8.1%,and the torsional modal is increased by 4.5%.3.According to the optimal conceptual design stage optimization model,a detailed finite element model was established and the basic performance analysis was performed.The bending stiffness was 8269 N·mm-1 and the torsional stiffness was 626967 N·m·rad"1.The first-order bending mode is 34.1Hz and the first-order torsional mode is 29.2Hz.The bending stiffness has reached the target value without the need for structural optimization,and the torsional stiffness and the first-order bending and torsion modes have not reached the target value and need to be structurally optimized.This paper presents two optimization methods:one is optimization of the ring structure,and the other is optimization of the wall thickness optimization method based on sensitivity analysis which is common in engineering applications.The final results of these two optimization methods are compared and analyzed while achieving the goal of optimization.Finally,the ring structure optimization is verified by experiments,which proves the rationality and high efficiency of the ring structure analysis.The optimization of the ring structure is effective and practical in engineering.The optimization of the ring structure has certain guiding significance for the optimization of the car body design. |
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